Internal-combustion engine



f F. LANG Y INTERNAL COMBUSTION ENGINE Filed Dec. 24, 1926 Egg:

Patented.. 2, 1930 'Um'rrzur STAT-Es;

PATENT OFFICE FRANZ Lama-or :rumen-mum, annimmt, AssreNon To nonEaT noscn:`

f 4 mensmscmr'r, or STUTTGART, GERMANY INTEBNAL-COMBUSTION ENGINE Application n ledDecember 24, 19.116, Serial No.,156,960, and Ain. Germany October 8, 196.

it lets flow back onl that ortion of the fuel This invention relates to the arrangement of a non-return valvein the pipe extending from the fuel pump of an internal combustion en 'ne to the 'injection nozzle of the same, it ing understood that the engine is of the air-less injection type. With internal combustion engines of this type when the nozzle in closed position becomes leaky from any reason, compressed air and gases stillpresent in the cylinder may find access into thedelivery pipe extendingvfrom the fuel pump to :the injection nozzle'especially after the-engine has been stopped, and may `displace the .fuel from said-pipe. Whenthe engine is started again the fuel must first be filled run irre with fuel be ore thel engine can run. That may, under some circumstances,'require very considerable time. Further, airmay remain in the hiel pipe and causethe engine to ar y. 1 Troub es and `dilicultiessimilar to those mentioned above may also occur in regular service if the fuel pump is of that type in which a certain portion of the fuel contained in the delivery pipe is permittedV to flow back after every .delivery'stroke in order to relieve the pressurein this pipe revent thetroublesome tri from the nozzle'. for instance,in that position in which' the pressure in the delivery pipe is relieved, this pipe' ma? be blown empty, particularly Vthe nozz e is leaky.

.In orderl to obviate these and similar diiculties and disadvantages it has already been tem rarily and to g of the fuel proposed to insert into the delivery pipe any one of the generally known non-return valves which close automatically instantly a reversal of the direction of flow of the respective fluid` or liquid takes place. Itjis true that the disadvantagesstated can be obviated jposesin thereby butlthis favorable effect is compensated by the unfavorable one that the portlon of the pipe located between the valve and the^ nozzle cannot be relieved of pressure after every delivery stroke.

Now, to prevent also this latter vdisadvanj 119mmturn-valve just suited for theparticular purview. 4This valve is so designed that If' the fuel .pump stops,

if v lthe delivery is just about to cease.

which will ordinari y flow ack to relieve the pressure in the delivery pipe..

In order to ma-ke the invention clearer,

reference is made to the accompanying drawin inwhich igure 1 is a longitudinal section through the novel non-return valve and pump employed in connection therewith; glgure 2 is an end view of the pump cams, .an

l Figure 3 is a longitudinal section through a modification. A In both oonstructional forms, A denotes the fuel pump and 5 a branch or casing at-V tached to said pump just between it and the delivery pipe 12 which conducts the fuel to 'the nozzle B (Fig. 1). In the casing 5 1s a seat 6 for a cone 8 forming the free end of an axiall end of thls member is inserted into a pistonmovable member 7. The otherl like member 10, reciprocable in the bore 9 l helical compression spring 15.

Both pumps (Figs. 1 and 3)V are shown ili .thatpositionin which the piston is just about to arrive at its inner` dead-center position and The nozzle needle 14 has notyet seated but will do so almost immediately, say in the next"A second, and the fuel delivered can, therefore,

still pass through the nozzle;

Y With the pump shown in Fig. 1 the piston 19 is lifted by a cam 17 and depressed by a spring 18. The piston is enclosed in the cas- Aing 16, and is so positioned therein that its upper end engages the stem of the delivery opened and' kept open during the last portion of every delivery stroke and during the first portion of everysuction stroke. At the below the receding. piston either until the presvalve 20 in such a manner that the latter is ginning ofthe latter stroke a part of the fuel i -under pressure in thedelivery pipe will folsure has fallen to zero or until the delivery valve can close.

The lengthl of travel and the time of operation of the suction valve are controlled L and may be varied so as to vary thereby the amount of fuel delivered. The suction valve is controlled by a cam 22 through the intermediary of ashiftable member comprising a body member 23 and a screw 211l having threaded engagement therewith so that the total length of the combination member 23/24 can be varied. The cam 22 and said member 23/24 are shown in that position in which the suction valve is just being opened. 26 denotes the suction pipe.

When the internal combustion engine runs at high speed, the united members 7 and 10 are and remain shifted to the right (Fig. 1) so that the small amount of liquid fuel flowing back from the delivery pipe can pass through the helical groove of the thread 11 without producing a pressure of sufficient strength to move the member 7 against the seat 6. But, if the nozzle B should have become leaky, the pressure existing in the cylinder of the internal combustion engine could drive the fuel back when the pump is in that position in which the suction pipe and the delivery pipe are temporarily in indirect communication with each other. Such an occurrence is, however, prevented by the nonret-urn valve which closes the communication instantly when the liquid fuel forced back out of the pipe 12 cannot pass quickly enough through the grooves of the thread .to avoid the creation of pressure on the right-hand end of the member 10 suiicient to press the member 7 uponthe seat 6. It is true that the non-return valve is again opened at the'v next delivery stroke of the pump, but it is also true that it is closed again if the nozzle should be still leaky. v

The modification shown in Fig. 3 is distinguished from that shown in Fig. 1 chiefly by the branch or casing 5 being arranged vertically instead of laterally, and'by the member 10, or the members 10/7 respectively, be- Y ing subjected to the pressure of a compression spring 27.

the passages 33, A34 on the one side and they passages 36, 37 on the other side. By turning the piston the point in the stroke of the latter tial recess 32 is at certain times only in communication with the passage 33 but is always in communication with the passages 36 and 37 so that the latter can always conduct liquid fuel delivered to such recess back to the suction pipe 35. Y.

The load upon the member 7/8/10/11 relatively to its shape and Weight is such that its movement towards the seat 6 is retarded at least for such a length of time as is required for the lflowing back of the iuid to relieve the pressure in the delivery pipe. If care is taken that thel retardation lasts only as long as the pressure relieving time, or just a little longer, then the pressure existing in the cylinder cannot, in the case the nozzle having become leaky, drive back the fuel.

The invention can be used advantageously also' with motors operating with open nozzles wher-e there is a normal non-return valve built in behind the nozzle. Further, the in-v with motors having mechanically controlled nozzles.

Instead of helical grooves or screw threads, as at 11 in Figs. 1 and 3, fine longitudinal grooves or other grooves allowing communication between the spaces at the two ends of the member 10 can be used. In fact, any constructional shape permittin such communication can be made use o The drawing shows merely two examples.

I claim:

In combination with an internal combustion engine, a fuel supply pump, an injection nozzle, a conduit connectin the discharge side of said pump with sai nozzle, means for relieving the pressure in said conduit near the end of the pressure stroke of said pump,

.-an-d a non-return valve in said conduit o erable to allow fuel to iow in said con uit toward said pump when the pressure insaid vconduit does not exceed a predetermined pressure, said valve preventing fiow of fuel in Isaid conduit when the pressure exceeds said '.'1

predetermined pressure.

In testimony whereof I'have hereunto af` fixed my signature.

FRANZ LANG.

at which such communication is established or interrupted may be varied so that the amount of fuel delivered by the pump may be adjusted accordingly. The circumferen- 

